PROJECT SUMMARY Cerebral palsy (CP) is the most common pediatric neurological disorder. CP is caused by damage to brain areas during development. CP results in weakness, altered tone and abnormal coordination. In unilateral spastic CP (USCP), the damage has a unilateral predominance. Although CP is defined as a motor disability, approximately 80% of people with USCP have deficits in sensation that limit the extent of rehabilitation. There is a poor understanding of how the sensory and motor systems interact in children with USCP. Impairments in motor and sensory function have largely been studied in isolation (rather than together) in children with USCP, even though voluntary movement requires the integration of sensory and motor processing. Moreover, while the motor system is better-characterized, there is still a limited understanding of how the location, type, and size of a child?s lesion impacts sensorimotor processing. There is an urgent need to identify and quantify sensory factors that impair movement in children with USCP. Our long-term goal is to develop evidence-based ways to improve movement in children with USCP. The overall objective for this project is to determine how fine touch sensation and sensation of limb position contribute to movement deficits in children with USCP. To meet our goal, we must not only know how sensory systems impact impairment in movement, but we must determine how a child?s lesion and brain connectivity contributes to these impairments. Our central hypothesis is that sensory dysfunction plays a key role in the ability of children with USCP to engage in functional, skillful movements. We also hypothesize that damage to specific brain regions cause specific kinds of impairments. The rationale for the proposed work is that demonstration of a strong relationship between sensory impairments and movement deficits will steer the development of therapies that engage children in the use of sensory information during meaningful complex tasks, with the goal of boosting motor function. !